This invention relates to semiconductor fabrication and particularly to a dielectric material formed from a reoxidized high dielectric constant material and a process to create same.
Dielectric materials used in semiconductors are selected depending on the intended use. For example, in the dynamic random access memory (DRAM) device, storage cells require a storage capacitor as a means of storing a charge to represent data. It is usually therefore desirable to select a dielectric material that possesses a high dielectric constant in order to prevent charge leakage. This is even more desirable, as DRAM devices become more densely packed, to contain more bit storage capability per die than early generations.
Many capacitor dielectrics have been utilized in attempts to shrink capacitor size and still maintain sufficient charge storage capability. Some examples include, thin film nitrides, oxide/nitride combinations or ferroelectric materials to name a few. However, each of these dielectric films possess limitations, thus forcing ongoing research to find the ideal capacitive dielectric film.
The present invention develops a very promising capacitive dielectric film by special reoxidation techniques which will come apparent to one skilled in the art from the following disclosure.
One embodiment of the present comprises a method for oxidizing a dielectric for semiconductor device fabrication, by subjecting the dielectric to an ozone ambient, wherein the ozone ambient is selected from the group consisting of an ambient containing a presence of ultraviolet light and an ozone gas, an ambient containing an ozone gas or an ambient containing an NF3/ozone gas mixture.
Another embodiment of the present invention comprises a method for forming a dielectric in a wafer cluster tool for semiconductor device fabrication by the steps of:
forming nitride adjacent a layer by rapid thermal nitridation;
subjecting the nitride to an ozone ambient, wherein the ozone ambient is selected from the group consisting of an ambient containing a presence of ultraviolet light and ozone gas, an ambient containing an ozone gas or an ambient containing an NF3/ozone gas mixture.